Extendable mast



E. A. CAMBURN EXTENDABLE MAST May 28, 1957 Filed 001;. 7, 1950 2 Sheets-Sheet 1 INVENTOR ATTORNEY E. A. CAMBURN EXTENDABLE MAST May 28, 1957 Filed Oct. 7, 1950 2 Sheets-Sheet 2;

Q1 51G ATTORNEY United States Patent Ofice 2,792,717 Patented May 28, 1957 EXTENDABLE MAST Elwyn A; Camburn, Jackson, Mich., assignor to Camburn Sales'a Mfg. Corporation, Battle Creek, Mich, a cor-. poration of Michigan Application October 7, 1950, SerialNo. 188,975

4 Claims. (Cl. 189-26) This invention relates broadly to extendable masts; and inits specific phases to a new and improved antenna mast fortelevision sets, which not only facilitates initial erection but greatly aids in servicing the. antenna, and the rotor also if one be used.

Accordingly, among the objccts of the present inven-; tionhas been theprovision of a telescopic mast embody:- ing jack means whereby it can be readilyextended to the desired height after mounting in retracted condition, thereby simplifying erection and requiring fewer men than usual for the operation.

Another object has been to provide a jack-up mast which will readily enable location of the antenna at the most advantageous height for the best reception.

Yet another object has been to provide a jack-up mast which can easily be reduced in height for servicing any} part or parts mounted thereon.

A further object has been to provide a relatively simple and inexpensive construction, and yet one which would be advantageous from the standpoints of manufacture, sale, installation, service, and use.

Still further objects and advantages of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims, the annexed drawings and the following description sett ingforth in detail certain means for carrying out theinvention,suchdisclosed means illustrating, however, but: one. ofvarious' ways in which the principle of the invention may be used.

Fi ure 1 is a side" elevation, partl broken away and in section, showing'one form of the invention.

Figure 2 is a fragmentary opposite side elevation partly broken away and in section.

Figure 3 is a horizontal sectional view taken on line 3-3 of Figure 1 looking in the direction of the arrows.

Preferences have been disclosed in the drawings and will be rather specifically described herein, but attention is invited to the possibility of making variations within the scope of the invention as set forth in the claims.

In the preferred form of construction, disclosed in Figures 1 to 3, the mast includes a lower section 10, an intermediate section 11, and an upper section 12, all of said sections being preferably formed from standard steel tubing. The upper section 12 of course carries the antenna, and the rotor if one be used.

The lower mast section may be mounted in any suitable way. As shown, it is pivoted by means of a bolt 13 to a base bracket 14 swingable to any required angle. The upper end of this section 10 is provided with an apertured flange 15 for the attachment of guys 16, and within the lower end of this section 10 is provided a cushioning spring 17. This spring is supported upon the bolt 13 and is adapted to absorb the shock if the section 11 should be permitted to descend too fast whenever retracting the mast.

The intermediate mast section 11 is slidably telescoped within thelower section 10, and the upward movement of said section 11 may be limited by means of a cable 18, the upper end of which is secured to a pin 19 carried by the lower end of said section 11, while the lower end of said cable is anchored to the bolt 13. The upper end of the section 11 is provided with a flange 20 for the attachment of guys 21, and is provided also with an upstanding collar 22 which adjustably receives the upper mast section 12, said collar having set screws 23 for securing said section 12 in any position to which it may be adjusted.

A circular inclined lifting dog 24 and a circular inclined locking dog 25 surround the intermediate mast section 11 and are operatively associated with two levers 26 and 27 respectively. By means of lever 26 the dog 24 may beoperated to raise the mast section 11 step by step, and after each step, the dog 25 will hold said mast section 11 against descent. The lever 27 may be operated, how-: ever, to release the dog 25 whenever the mast section-11 is to be lowered, and provision is made whereby release of said lockingdog 25 will also release the liftingdog 24. Thus, by alternately moving the locking dog 25 to released position and operative position, the mast section 11 may be lowered step by step, or if safe to do so, thedogs may be held released and the section 11 permitted to continuously descend.

The lever 26 is fulcrumed at 28 to a lug 29 which is secured to and projects upwardly from the flange 15, and the inner end of this lever is connected by means of a link 30 with a peripheral lug 31 on the lifting dog 24. A spring 32 is connected at its upper end to the inner end of lever 26, and at 33 the lower end of said spring is anchored to the mast section 10. This spring exerts a downward pull on the inner end of the lever 26 and normally holds it yieldably against a stop 34 on the lug 29, and the link 30 then supports the dog 24 in an inclined position in which its inner edge is in contact with the mast section 11 in readiness to tightly grip and lift the latter whenever the lever 26 is pulled downwardly.

The locking dog 25 is pivoted at 35 to a second lug 36 which is secured to and projects upwardly from the flange 15 and at a point, diametrically opposite the pivot 35, pull springs 37 are connected with said dog to nor m-ally hold it in an inclined position tightly engaged with the mast section 11, said pull springs being anchored to the flange 15. The dog 25 thus supports the mast section 11 until released by downwardly pulling the lever27.- A- thrust member 38'- is provided to. transmit the releasing movement of the. locking dog 25 to the lifting dog 24, said thrust member being shown in the form of a bolt having its upper end adjustably secured by nuts 39 to the lower end of the lifting dog 24, the lower end of said bolt being normally spaced a slight distance above the low end of the locking dog 25.

The elevating of tubular member 11 thus merely involves applying appropriate pulling force in downward direction on the outer end of arm 26 which moves lifting dog 24 upward and with it tube 11 which is gripped by the lifting dog. On the other hand locking dog 25 only holds tube 11 against downward movement and accordingly tube 11 is free to be moved upward through locking dog 25 Without pull-ing down on the outer end of arm 27 due to this one way gripping of locking dog 25 on tube 11.

The levers 26 and 27 may be directly operated from a ladder placed against the mast section 10, or may be provided with depending operating cables 40 and 41, respectively, said cables extending to the lower end of said mast section 10. Each lever is preferably provided with a foldable outer section, as shown, to reduce the transverse dimension of the mast for storage and shipment, as seen in dotted lines in Figure 2. The foldable section of lever 26 is denoted at 26, and that of lever 27 at 27. These sections are pivoted near their inner ends as shown at 26 and 27 respectively, and said inner ends are provided with stops 26 and 27 which normally underlie portions of the fulcrums 28 and 35, respectively, whereby each lever operates as if it were of one-piece construction, insofar as its dog operating function is concerned.

From the foregoing description and the accompanying drawings, it will be seen that a novel and effective combination has been shown for attaining the desired ends, and while preferences have been disclosed, attention is again invited to the possibility of making variations in the tower extending and retracting assembly for accomplishing the same results.

Other modes of applying the principle of my invention may beemployed instead of the one explained, change being made as regards the apparatus herein disclosed, provided the means stated by any of the following claims, or. the equivalent of such stated means, be employed.

. I therefore particularly point out and distinctly claim as my invention:

1. An extensible mast or similar device comprising a lower tubular section, a second section within and slidable lengthwise of said lower section, said lower section having a guy supporting flange on its upper end, a pair of lugs projecting upwardly from said flange and spaced from the periphery of said second section, a lever fulcrumed near one end thereof to one of said lugs, a spring connected to said lever and said first section for lowering said one end thereof, stop means supported by said first section for limiting the movement of said lever under the influence of said spring, a link pivoted to and extending upwardly from said one end of said lever, an inclined lifting dog surrounding and engaging said second section, the high end of said lifting dog being pivoted to the upper end of said link, an inclined locking dog surrounding and engaging said second section in downwardly spaced relation with said lifting dog, means pivotally mounting the high end of said locking dog upon the other of the aforesaid lugs, spring means urging said locking dog downward into engagement with said second section, a releasing lever connected with the high end of said locking dog, and means disposed between said dogs and adjustably connected to one thereof for automatically releasingsaid lifting dog when said locking dog is released.

2. A structure as specified in claim-1; said means for automatically releasing said lifting dog consisting of a thrust bolt having a threaded end adjustably connected to the lower end of said lifting dog and having a free end normally in slightly spaced relation to the lower end arcane of said locking dog, whereby releasing movement of said locking dog is transmitted to said lifting dog.

3. An extensible mast or similar device comprising a lower tubular section having a guy supporting flange projecting laterally outwardly therefrom and adjacent the upper end thereof, a second section telescopically fitting within and upwardly slidable from said lower section, a combination elevating and lowering means which includes a lifting dog, a locking dog, and fixed location pivots on said flange with both of said dogs carried on said pivots and surrounding and engageable with said second section above said lower section, lever means pivotally supported on said flange for operating said lifting dog to raise said second section step-by-step, said locking dog holding said second section against descent after each raising step thereof, lever means pivotally supported on said flange for operating said locking dog, and adjustable means for automatically releasing said lifting dog when said locking dog is operated to lower said second section.

4. A structure as specified in claim 3; wherein said means for operating said lifting dog includes a depending pull memberfor effecting upward movement of said lifting dog, and spring means for causing return of said lifting dog and return of said pull member to starting position after each pull upon the latter, said means for operating said locking dog including a depending pull member for releasing said locking dog, spring means for returning said locking dog to starting position after each pull upon 'said release member, and an adjustable member between said lifting dog and said locking dog such that operating said locking dog upon pulling said release member for same a predetermined distance will release said lifting dog and allow said second section to be lowered within limits of its movement range.

References Cited in the file of this patent UNITED STATES PATENTS 236,348 Mickey Jan. 4, 1881 836,303 Christensen Nov. 20, 1906 964,594 Wileman et al July 19, 1910 1,031,185 Krulish July 2, 1912 1,036,496 Humphrey Aug, 20, 1912 1,110,961 Renter Sept. 15, 1914 1,154,687 Bogle Sept. 28, 1915 1,349,576 Markham Aug. 17, 1920 1,901,726 Bonnet Mar. 14, 1933 2,065,715 Leon Dec. 29, 1936 2,092,669 Greve Sept. 7, 1937 2,174,321 Gunn Sept. 26, 1939 2,194,386 Dunaway Mar. 19, 1940 M, hail 

